Condensed Financial Information - Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Assets:
Cash and cash equivalents	$ 37,299	$ 38,227	$ 30,558	$ 25,539
Total assets	392,647	372,229	297,119
Liabilities and Shareholders' Equity:
Total liabilities	223,686	209,295
Shareholders' equity	164,850	157,318
Total liabilities and stockholders' equity	392,647	372,229
Berkshire Hathaway (Parent) [Member]
Assets:
Cash and cash equivalents	7,289	6,616	5,985	2,913
Investments in fixed maturity and equity securities	38	304
Investments in and advances to/from consolidated subsidiaries	166,219	159,036
Other assets	49	27
Total assets	173,595	165,983
Liabilities and Shareholders' Equity:
Accounts payable, accrued interest and other liabilities	129	45
Income taxes	329	260
Notes payable and other borrowings	8,287	8,360
Total liabilities	8,745	8,665
Shareholders' equity	164,850	157,318
Total liabilities and stockholders' equity	$ 173,595	$ 165,983